DirectShow SetFormat fails on second call

freestar8n

I'm having difficulty using DirectShow to set the capture format for ASI cameras - both an ASI1600 and ASI290. I need to call SetFormat to change the capture resolution.

I can enumerate all the capabilities as usual - but when I use GetStreamCaps to select one of the formats - and then a SetFormat, the SetFormat works the first time for the first capability, but not the second time for the next capability. The same code works fine for many other cameras.

Can someone please confirm if this should work or not?

Thanks,

Frank

chad

Confused with your words, which software do you use? how can I repeat this issue?

Thanks

Chad

freestar8n

Hi-

I am the author of MetaGuide, which is a C++ DirectShow app that connects to video cameras via DirectShow and provides guiding and collimation tools.

So - I am talking about C++ code that is trying to set the size of the capture frame - based on the enumerated capabilities provided by the camera.

Normally you ask the camera to enumerate its resolutions - and then you select the format that is a best match to what you want. And normally you can just tell the camera to SetFormat for one of the resolutions that it says it supports. But the ASI DirectShow driver gives an error if you ever try to set two different formats in succession. Other cameras do allow this.

The driver returns 0x80040200, which is "Invalid media type". But the format comes directly from the camera as one that it supports and I haven't changed it at all.

I see that applications like SharpCap and AmCap do allow changing the capture resolution of the camera - but they appear to do it using the pin's property page - rather than using the DirectShow API as I am doing.

Does this help answer your question? It may have something to do with an obscure x64 vs. x32 issue. But I first wanted to confirm that your dshow driver does allow normal usage of SetFormat.

If this still isn't clear I can try to create a small standalone C++ example that works with other cameras, but does not work with yours.

Thanks for any assistance-

Frank

chad

Hi Frank,

sorry for the problem.

Can we reproduce this problem using the version on your website? If it could, please tell me the detailed steps.

Usually, we use SharpCap to make the test, so did not get this bug report before.

Thanks

Chad

freestar8n

Hi-

Yes - if you install the latest MetaGuide *beta* on the web page:

https://www.astrogeeks.com/Bliss/MetaGuide/index.html

which is 5.3.2 (you need to do a full install of 5.2.6 first per the instructions) you should be able to make it try to use lower resolution, and it will fail. This would only help you if you can see under the covers what your directshow driver is doing in reponse to the requests from MG - but if that is possible it may provide insight.

The beta is needed because the 5.2.6 version didn't work with the asi1600. That is fixed in the beta.

But I realize my issue may not affect other apps - so I understand it may not be high priority. But if someone could look into it that would be great.

Just start MG and connect to the camera - and it should connect at full res.

Open the Setup dialog and enter a smaller resolution - like 1000 x 1000. It doesn't have to be an exact match because MG will then ask the camera what resolution it provides - and it will choose the closest match. But for ASI cameras, the SetFormat doesn't work- and it reverts to full res.

The directshow response from the asi1600 indicates 34 possible video formats - which is great and it looks correct. But I should be able to query and set them one after another to test them out - but it only lets me set one - and after that it says "bad media format." Other cameras work fine.

Thanks,

Frank

chad

Hi Frank,

I checked the issue.

It should be caused by the following reasons. When we developed the DriectShow driver at begining, for resolution, we meet a problem. For Application, there are 2 ways to set the new resolution: By the dialog created by us, and by the application directly.

The attachment is created by SharpCap.

Then we meet a problem, there's no way to synchronize the two side. There is no interface to sync inside the DirectShow. At last, we got a deal, If you want to set a new resolution, you should stop capture first. Then set the index of new resolution, and start it again.

If you use sharpcap to make a test, you will find that point, when you open the resolution dialog of us, the capture is stopped.

So I think you should call stop capture to set the new resolution, and start it again.

Thanks

Chad

freestar8n

Hi-

Thanks for looking into it. My code is generic to all DirectShow cameras, so I want to try to avoid writing anything application specific. I also want to avoid needing the user to open up the filter dialog.

When I do SetFormat, the filter graph isn't running and capture isn't happening. I simply install the capture device in the filter graph and then try setting the different formats. This is what you need to do if you want to find out the maximum frame rate and other things for each format.

So - the camera should never be actually capturing and the filter graph isn't running while I do this.

I was mainly checking to see if perhaps I was doing something wrong - but if it's likely the filter does behave this way - I will see if I can find some kind of programmatic workaround.

Thanks for looking into it - I'll see what I can come up with.

Frank

chad

Hi Frank，

So please keep in touch.

Thanks

Chad